src: throw on a malformed localStorage file

[TrevorBurnham]

Fixes: #65878
Fixes: #64640

src/node_webstorage.cc asserted the SQLite type of every column it read. But the backing file is a user-specified path, and the schema is created with CREATE TABLE IF NOT EXISTS, so a file that already contains tables of those names is adopted as-is and its values may have any type. A wrong-typed schema_version is the worst case: the assertion is in Storage::Open(), so any access aborts and the application can't inspect or repair the file first.

This PR makes localStorage methods throw ERR_INVALID_STATE in that scenario:

$ node --localstorage-file=/tmp/ws.db -e "localStorage.length"
Error: localStorage database is malformed: expected schema_version to be an integer
  code: 'ERR_INVALID_STATE'

Making these paths non-fatal exposed three further problems, all fixed here:

• The connection leaked on every failed open. Open() only adopted the sqlite3* into db_ at the very end, so an early return dropped it, and because db_ stayed null the next access opened another. The old CHECK aborted on the first attempt, so this never accumulated; now a try { localStorage.length } catch {} loop leaked two descriptors per iteration until the limit was exhausted and the error degraded into unable to open database file. This is Web Storage Maybe leaks SQLite connections when database initialization fails #64640.
• Storage::GetAll() ignored errors. It checked neither the result of sqlite3_prepare_v2() nor the status its row loop ended on, so a pre-existing table missing a column, or a corrupt read mid-scan, was reported to the inspector as an empty store while every JavaScript accessor threw for the same file. Both now return std::nullopt.
• A remote debugger still aborted, which is the second commit. Protocol messages from a remote frontend are dispatched from a libuv callback with no HandleScope on the stack, inside the SealHandleScope that MainThreadInterface::DispatchMessages() installs, so throwing from Open() was fatal: FATAL ERROR: v8::HandleScope::CreateHandle() Cannot create a handle without a HandleScope. Every Open() failure was affected, including a --localstorage-file that names a directory, so this did not need a malformed file to reach. getWebStorage() already opens a HandleScope and a TryCatch for its own handle use; the GetAll() call now does the same.

Storage::GetAll() reports failure with std::optional rather than throwing, because its only caller is the inspector agent and a pending exception there has no JavaScript to propagate to. Storage::Length() keeps its CHECK: its query is SELECT count(*), which is always an integer.

Tests

New tests cover the four JavaScript-reachable assertions and the descriptor leak in test-webstorage.js, plus both inspector failures in a new test-inspector-dom-storage-malformed.js.

Out of scope

One possible follow-up: THROW_SQLITE_ERROR uses sqlite3_errstr(code), so a prepare failure reports SQL logic error rather than no such column: schema_version. Switching it to sqlite3_errmsg(db) would improve every throw in the file.

[nodejs-github-bot]

Review requested:

• @nodejs/inspector

[codecov]

Codecov Report

❌ Patch coverage is 33.33333% with 20 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.18%. Comparing base (9f7ae86) to head (43e1abd).
⚠️ Report is 15 commits behind head on main.

Files with missing lines	Patch %	Lines
src/inspector/dom_storage_agent.cc	14.28%	10 Missing and 2 partials ⚠️
src/node_webstorage.cc	50.00%	4 Missing and 4 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #65879      +/-   ##
==========================================
- Coverage   90.19%   90.18%   -0.02%     
==========================================
  Files         771      771              
  Lines      264911   265116     +205     
  Branches    50323    50358      +35     
==========================================
+ Hits       238939   239087     +148     
- Misses      16922    16978      +56     
- Partials     9050     9051       +1     

Files with missing lines	Coverage Δ
src/node_webstorage.h	83.33% <ø> (ø)
src/node_webstorage.cc	77.64% <50.00%> (+2.70%)	⬆️
src/inspector/dom_storage_agent.cc	81.41% <14.28%> (-4.91%)	⬇️

... and 32 files with indirect coverage changes

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